Authorization Commands

Syntax Description

network	Runs authorization for all network-related service requests, including SLIP, PPP, PPP NCPs, and ARA.
exec	Runs authorization to determine if the user is allowed to run an EXEC shell. This facility might return user profile information such as autocommand information.
commands	Runs authorization for all commands at the specified privilege level.
level	Specific command level that should be authorized. Valid entries are 0 through 15.
reverse-access	Runs authorization for reverse access connections, such as reverse Telnet.
default	Uses the listed authorization methods that follow this argument as the default list of methods for authorization.
list-name	Character string used to name the list of authorization methods.
method1 [method2...]	One of the keywords listed in Table 10.

Defaults

Authorization is disabled for all actions (equivalent to the method keyword none). If the aaa authorization command for a particular authorization type is issued without a named method list specified, the default method list is automatically applied to all interfaces or lines (where this authorization type applies) except those that have a named method list explicitly defined. (A defined method list overrides the default method list.) If no default method list is defined, then no authorization takes place.

Command Modes

Global configuration

Command History

Release	Modification
10.0	This command was introduced.
12.0(5)T	Group server support was added as various method keywords for this command.

Usage Guidelines

Use the aaa authorization command to enable authorization and to create named methods lists, defining authorization methods that can be used when a user accesses the specified function. Method lists for authorization define the ways authorization will be performed and the sequence in which these methods will be performed. A method list is simply a named list describing the authorization methods to be used (such as RADIUS or TACACS+), in sequence. Method lists enable you to designate one or more security protocols to be used for authorization, thus ensuring a backup system in case the initial method fails. Cisco IOS software uses the first method listed to authorize users for specific network services; if that method fails to respond, the Cisco IOS software selects the next method listed in the method list. This process continues until there is successful communication with a listed authorization method, or all methods defined are exhausted.

Note The Cisco IOS software attempts authorization with the next listed method only when there is no response from the previous method. If authorization fails at any point in this cycle---meaning that the security server or local username database responds by denying the user services---the authorization process stops and no other authorization methods are attempted.

Use the aaa authorization command to create a list by entering the list-name and the method, where list-name is any character string used to name this list (excluding all method names) and method identifies the list of authorization method(s) tried in the given sequence.

Note In Table 10, the group radius, group tacacs+, and group group-name methods refer to a set of previously defined RADIUS or TACACS+ servers. Use the radius-server host and tacacs-server host commands to configure the host servers. Use the aaa group server radius and aaa group server tacacs+ commands to create a named group of servers.

Cisco IOS software supports the following six methods for authorization:

• RADIUS---The network access server requests authorization information from the RADIUS security server group. RADIUS authorization defines specific rights for users by associating attributes, which are stored in a database on the RADIUS server, with the appropriate user.

• TACACS+---The network access server exchanges authorization information with the TACACS+ security daemon. TACACS+ authorization defines specific rights for users by associating attribute-value (AV) pairs, which are stored in a database on the TACACS+ security server, with the appropriate user.

• If-Authenticated---The user is allowed to access the requested function provided the user has been authenticated successfully.

• None---The network access server does not request authorization information; authorization is not performed over this line/interface.

• Local---The router or access server consults its local database, as defined by the username command, to authorize specific rights for users. Only a limited set of functions can be controlled via the local database.

• Kerberos Instance Map---The network access server uses the instance defined by the kerberos instance map command for authorization.

Method lists are specific to the type of authorization being requested. AAA supports four different types of authorization:

• Network---Applies to network connections. This can include a PPP, SLIP, or ARA connection.

• EXEC---Applies to the attributes associated with a user EXEC terminal session.

• Commands---Applies to the EXEC mode commands a user issues. Command authorization attempts authorization for all EXEC mode commands, including global configuration commands, associated with a specific privilege level.

• Reverse Access---Applies to reverse Telnet sessions.

When you create a named method list, you are defining a particular list of authorization methods for the indicated authorization type.

Once defined, method lists must be applied to specific lines or interfaces before any of the defined methods will be performed.

The authorization command causes a request packet containing a series of AV pairs to be sent to the RADIUS or TACACS daemon as part of the authorization process. The daemon can do one of the following:

• Accept the request as is.

• Make changes to the request.

• Refuse the request and refuse authorization.

For a list of supported RADIUS attributes, refer to the "RADIUS Attributes" appendix in the
Cisco IOS Security Configuration Guide. For a list of supported TACACS+ AV pairs, refer to the "TACACS+ Attribute-Value Pairs" appendix in the Cisco IOS Security Configuration Guide.

Note There are five commands associated with privilege level 0: disable, enable, exit, help, and logout. If you configure AAA authorization for a privilege level greater than 0, these five commands will not be included in the privilege level command set.

Examples

The following example defines the network authorization method list named scoobee, which specifies that RADIUS authorization will be used on serial lines using PPP. If the RADIUS server fails to respond, then local network authorization will be performed.

aaa authorization network scoobee group radius local

Related Commands

Command	Description
aaa accounting	Enables AAA accounting of requested services for billing or security purposes.
aaa new-model	Enables the AAA access control model.

Syntax Description

This command has no arguments or keywords.

Defaults

After the aaa authorization commands level method command has been issued, this command is enabled by default---meaning that all configuration commands in the EXEC mode will be authorized.

Command Modes

Global configuration

Command History

Release	Modification
11.2	This command was introduced.

Usage Guidelines

If aaa authorization commands level method command is enabled, all commands, including configuration commands, are authorized by AAA using the method specified. Because there are configuration commands that are identical to some EXEC-level commands, there can be some confusion in the authorization process. Using the no aaa authorization config-commands command stops the network access server from attempting configuration command authorization.

After the no form of this command has been entered, AAA authorization of configuration commands is completely disabled. Care should be taken before entering the no form of this command because it potentially reduces the amount of administrative control on configuration commands.

Use the aaa authorization config-commands command if, after using the no form of this command, you need to reestablish the default set by the aaa authorization commands level method command.

Examples

The following example specifies that TACACS+ authorization is run for level 15 commands and that AAA authorization of configuration commands is disabled:

aaa new-model
aaa authorization command 15 group tacacs+ none
no aaa authorization config-commands

Related Commands

Command	Description
aaa authorization	Sets parameters that restrict network access to a user.

Syntax Description

group radius	Specifies that the network access server will request authorization from a RADIUS security server before allowing a user to establish a reverse Telnet session.
group tacacs+	Specifies that the network access server will request authorization from a TACACS+ security server before allowing a user to establish a reverse Telnet session.

Defaults

The default for this command is disabled, meaning that authorization for reverse Telnet is not requested.

Command Modes

Global configuration

Command History

Release	Modification
11.3	This command was introduced.
12.0(5)T	Group server support was added as various method keywords for this command.

Usage Guidelines

Telnet is a standard terminal emulation protocol used for remote terminal connection. Normally, you log in to a network access server (typically through a dialup connection) and then use Telnet to access other network devices from that network access server. There are times, however, when it is necessary to establish a reverse Telnet session. In reverse Telnet sessions, the Telnet connection is established in the opposite direction---from inside a network to a network access server on the network periphery to gain access to modems or other devices connected to that network access server. Reverse Telnet is used to provide users with dialout capability by allowing them to Telnet to modem ports attached to a network access server.

It is important to control access to ports accessible through reverse Telnet. Failure to do so could, for example, allow unauthorized users free access to modems where they can trap and divert incoming calls or make outgoing calls to unauthorized destinations.

Authentication during reverse Telnet is performed through the standard AAA login procedure for Telnet. Typically the user has to provide a username and password to establish either a Telnet or reverse Telnet session. This command provides an additional (optional) level of security by requiring authorization in addition to authentication. When this command is enabled, reverse Telnet authorization can use RADIUS or TACACS+ to authorize whether or not this user is allowed reverse Telnet access to specific asynchronous ports, after the user successfully authenticates through the standard Telnet login procedure.

Examples

The following example causes the network access server to request authorization information from a TACACS+ security server before allowing a user to establish a reverse Telnet session:

aaa new-model
aaa authentication login default group tacacs+
aaa authorization reverse-access default group tacacs+
!
tacacs-server host 172.31.255.0
tacacs-server timeout 90
tacacs-server key goaway
 

The lines in this sample TACACS+ reverse Telnet authorization configuration are defined as follows:

• The aaa new-model command enables AAA.

• The aaa authentication login default group tacacs+ command specifies TACACS+ as the default method for user authentication during login.

• The aaa authorization reverse-access default group tacacs+ command specifies TACACS+ as the method for user authorization when trying to establish a reverse Telnet session.

• The tacacs-server host command identifies the TACACS+ server.

• The tacacs-server timeout command sets the interval of time that the network access server waits for the TACACS+ server to reply.

• The tacacs-server key command defines the encryption key used for all TACACS+ communications between the network access server and the TACACS+ daemon.

The following example configures a generic TACACS+ server to grant a user, "jim," reverse Telnet access to port tty2 on the network access server named "site1" and to port tty5 on the network access server named site2:

user = jim
  login = cleartext lab
  service = raccess {
    port#1 = site1/tty2
    port#2 = site2/tty5
}

Note In this example, "site1" and "site2" are the configured host names of network access servers, not DNS names or alias.

The following example configures the TACACS+ server (CiscoSecure) to authorize a user named Jim for reverse Telnet:

user = jim
 profile_id = 90
 profile_cycle = 1
 member = Tacacs_Users
 service=shell {
 default cmd=permit
 }
 service=raccess {
 allow "c2511e0" "tty1" ".*"
 refuse ".*" ".*" ".*"
 password = clear "goaway"
 

Note CiscoSecure only supports reverse Telnet using the command line interface in versions 2.1(x) through version 2.2(1).

An empty "service=raccess {}" clause permits a user to have unconditional access to network access server ports for reverse Telnet. If no "service=raccess" clause exists, the user is denied access to any port for reverse Telnet.

For more information about configuring TACACS+, refer to the "Configuring TACACS+" chapter in the Cisco IOS Security Configuration Guide. For more information about configuring CiscoSecure, refer to the CiscoSecure Access Control Server User Guide, version 2.1(2) or later.

The following example causes the network access server to request authorization from a RADIUS security server before allowing a user to establish a reverse Telnet session:

aaa new-model
aaa authentication login default group radius
aaa authorization reverse-access default group radius
!
radius-server host 172.31.255.0
radius-server key goaway
 

The lines in this sample RADIUS reverse Telnet authorization configuration are defined as follows:

• The aaa new-model command enables AAA.

• The aaa authentication login default group radius command specifies RADIUS as the default method for user authentication during login.

• The aaa authorization reverse-access default group radius command specifies RADIUS as the method for user authorization when trying to establish a reverse Telnet session.

• The radius-server host command identifies the RADIUS server.

• The radius-server key command defines the encryption key used for all RADIUS communications between the network access server and the RADIUS daemon.

The following example configures the RADIUS server to grant a user named "jim" reverse Telnet access at port tty2 on network access server site1:

Password = "goaway"
User-Service-Type = Shell-User
cisco-avpair = "raccess:port#1=site1/tty2"
 

An empty "raccess:port#1=nasname1/tty2" clause permits a user to have unconditional access to network access server ports for reverse Telnet. If no "raccess:port#1=nasname1/tty2" clause exists, the user is denied access to any port for reverse Telnet.

For more information about configuring RADIUS, refer to the "Configuring RADIUS" chapter in the Cisco IOS Security Configuration Guide.

Syntax Description

arap	Enables authorization for line(s) configured for AppleTalk Remote Access (ARA) protocol.
commands	Enables authorization on the selected line(s) for all commands at the specified privilege level.
level	Specific command level to be authorized. Valid entries are 0 through 15.
exec	Enables authorization to determine if the user is allowed to run an EXEC shell on the selected line(s).
reverse-access	Enables authorization to determine if the user is allowed reverse access privileges.
default	(Optional) The name of the default method list, created with the aaa authorization command.
list-name	(Optional) Specifies the name of a list of authorization methods to use. If no list name is specified, the system uses the default. The list is created with the aaa authorization command.

Defaults

Authorization is not enabled.

Command Modes

Line configuration

Command History

Release	Modification
11.3 T	This command was introduced.

Usage Guidelines

After you enable the aaa authorization command and define a named authorization method list (or use the default method list) for a particular type of authorization, you must apply the defined lists to the appropriate lines for authorization to take place. Use the authorization command to apply the specified method lists (or if none is specified, the default method list) to the selected line or group of lines.

Examples

The following example enables command authorization (for level 15) using the method list named charlie on line 10:

line 10
 authorization commands 15 charlie

Related Commands

Command	Description
aaa authorization	Sets parameters that restrict network access to a user.